Water purification device, and method using water purification device to filter water

ABSTRACT

A water purification device, including a first pressure cylinder, a second pressure cylinder, a first connecting piece and a second cylinder block arranged successively from bottom to top, and further comprising a first cylinder block arranged inside the second cylinder block. The first pressure cylinder and the second pressure cylinder both are open at one end and formed with a first through-hole at the other end; the first cylinder block and the second cylinder block both are open at two ends and arranged in a hollow shape. A water inlet, which is communicated with first flow passages formed between the first cylinder block and the second cylinder block, is formed on the second cylinder block, and a water outlet pipe, communicated with the first cylinder block, is inserted into an outer wall of the water purification device.

FIELD OF THE INVENTION

The invention relates to the field of sewage treatment, and moreparticularly to a water purification device and a method using waterpurification device to filter water.

BACKGROUND OF THE INVENTION

China is a country very short of water resources, seriously affectingpeople's living conditions. In recent years, the problem on urban andrural domestic sewage has become prominent, and the domestic sewage frommany urban residents is subject to centralized treatment after flowingtogether into a sewerage network. However, the sewerage network is stillnot established in some towns and in the vast rural areas due to thedisequilibrium of economic and social development, so that the dischargeof the domestic sewage is in a disordered state with universalphenomenon of discharging the sewage directly and indiscriminately,resulting in the deterioration of water quality in some rivers andincreasing the contribution rate to the water pollution year by year. Ifthings continue this way, it surely will greatly threaten people'shealth. Therefore, people have to devote greater effort in the sewagetreatment in order to relieve stress on sewage treatment.

In the sewage treatment, substances of larger particle size, e.g.sediment, are usually removed from the sewage by filtering first, andthen substances of smaller particle size, e.g. rust stains and bacteria,are further removed from the sewage, and finally soluble salts are alsorequired to be removed from the sewage. The sewage becomes more cleanafter being treated in three ways, but, an ultrafiltration membranecannot be recycled in the treatment process, so that the ultrafiltrationmembrane with a higher cost is required to be replaced frequently,resulting in the increase of the cost of water purification. During thesewage purification, the cost of a filter membrane is usually too highto energetically popularize the sewage purification.

SUMMARY OF THE INVENTION

A main objective of the invention is to provide a water purificationdevice to solve the problem of high cost of water purification due tofrequent replacement of filter membranes in the existing waterpurification process.

To achieve the above objective, the invention provides a waterpurification device, comprising a first pressure cylinder, a secondpressure cylinder, a first cylinder block, a second cylinder block and afirst connecting piece; the first pressure cylinder, the second cylinderblock, the first connecting piece and the second pressure cylinder aresuccessively connected to each other, and the first cylinder block isaccommodated in the second cylinder block;

The first cylinder block is configured to accommodate an ultrafiltrationmembrane for filtering water; two opposite ends of the first cylinderblock are provided with openings arranged in a hollow shape, and twoopposite ends of the second cylinder block are provided with openingsarranged in a hollow shape; the first pressure cylinder comprises afirst water flow end provided with an opening for the water to flow anda drainage end formed with a first through-hole for discharging stains,and the first pressure cylinder is arranged in a hollow shape; thesecond pressure cylinder comprises a second water flow end provided withan opening for the water to flow and a water inlet end formed with asecond through-hole for the external water to flow into the secondpressure cylinder, and the second pressure cylinder is arranged in ahollow shape; and a third through-hole for the water to flow is formedon the first connecting piece;

One end of the second cylinder block is connected to the first waterflow end, and the other end thereof is connected to the second waterflow end through the first connecting piece; first flow passages, oneend of which near the first connecting piece is sealed by the firstconnecting piece, are formed between the first cylinder block and thesecond cylinder block and communicated with the first pressure cylinder;the first cylinder block and the second pressure cylinder arecommunicated with each other through the third through-hole; a waterinlet communicated with the first flow passage is formed on an outerwall of the second cylinder block, and a water outlet pipe communicatedwith the first cylinder block is further inserted into the outer wall ofthe second cylinder block;

Prior to the water filtration of the water purification device, thefirst through-hole is in a closed state and the second through-hole isin an open state; during the filtration, the first through-hole isopened and the second through-hole is closed; during flushing theultrafiltration membrane in the first cylinder block, the water inletand the water outlet pipe are closed and the first through-hole isopened, so that the water flows into the first cylinder block from thesecond through-hole and flows out of the first through-hole.

Preferably, a second connecting piece, which is configured to connectthe first cylinder block and the second cylinder block to the firstpressure cylinder, is further arranged between the second cylinder blockand the first pressure cylinder; first diversion holes configured tocommunicate the first flow passage with the first pressure cylinder andsecond diversion holes configured to communicate the first cylinderblock with the first pressure cylinder are arranged on the secondconnecting piece.

Preferably, the second connecting piece comprises a first connectingplate having a through-hole formed thereon, a periphery of thethrough-hole extends in a direction deviated from a surface of the firstconnecting plate to form a first circular cylinder, and a first bafflefor closing ports of the first circular cylinder is arranged at one endof the first circular cylinder away from the first connecting plate, andthe second diversion holes are arranged on the first baffle; peripheriesof the second diversion holes extend in a direction deviated from asurface of the first baffle to form a second circular cylinder, and thefirst diversion holes are further arranged on the first baffle on theperiphery of the second circular cylinder; the first circular cylinderis located between the first connecting plate and the second circularcylinder, and the caliber of the first circular cylinder is greater thanthat of the second circular cylinder.

Preferably, the first circular cylinder is perpendicular to the firstconnecting plate and the second circular cylinder is perpendicular tothe first baffle.

Preferably, a second baffle for closing ports of the second circularcylinder is arranged at one end of the second circular cylinder awayfrom the first baffle, and a pressurizing hole is formed on the secondbaffle.

Preferably, a first reinforcer, connected to the second connectingpiece, is sleeved at a position on the first water flow endcorresponding to an outer wall of the first pressure cylinder.

Preferably, a second reinforcer, connected to the first connectingpiece, is sleeved at a position on the second water flow endcorresponding to an outer wall of the second pressure cylinder.

Preferably, the cross-sectional area of an end face of the drainage endparallel to the first water flow end gradually decreases from the firstwater flow end to the drainage end.

Preferably, a first drain pipe is inserted into the first through-holeand a second drain pipe is inserted into the second through-hole, andwater flow regulating valves are arranged on both of the first drainpipe and the second drain pipe.

Preferably, the first cylinder block and the second cylinder block arearranged in a shape of hollow cylinder.

The invention further provides a method using the water purificationdevice according to any one of items to filter water, wherein the methodcomprises the following steps of:

a. placing an ultrafiltration membrane in the first cylinder block;

b. closing the first through-hole and opening the second through-hole,and injecting the water to be filtered into the flow passages throughthe water inlet so as to exhaust the gas in the first cylinder block andthe second pressure cylinder; and

c. keeping the first through-hole closed, and keeping the secondthrough-hole open or intermittently open so as to filter the water.

According to the water purification device disclosed by the invention,the water is forced into the ultrafiltration membrane under the actionof the water pressure and the first pressure cylinder. After thefiltration, the sewage is discharged from the drainage end, and theclean water is guided out through the water outlet pipe. In case thatthe ultrafiltration membrane is required to be cleaned, only the waterflow is required to be guided into the water purification device throughthe second through-hole, and the stains remaining in the ultrafiltrationmembrane can be flushed away under the action of the water pressure soas to prevent the ultrafiltration membrane from being clogged andscrapped due to accumulation of excessive stains, thereby greatlyimproving the service life of the ultrafiltration membrane and reducingthe cost of water purification.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a stereoscopic structure diagram of an embodiment of a waterpurification device according to the invention;

FIG. 2 is a structure diagram of a first pressure cylinder of the waterpurification device in FIG. 1;

FIG. 3 is a structure diagram of a second pressure cylinder of the waterpurification device in FIG. 1;

FIG. 4 is a structure diagram of a second connecting piece of the waterpurification device in FIG. 1;

FIG. 5 is a structure diagram of a first connecting piece of the waterpurification device in FIG. 1;

FIG. 6 is a structural schematic plan from a side view of the waterpurification device in FIG. 1;

FIG. 7 is a structural schematic plan from another view of the waterpurification device in FIG. 6;

FIG. 8 is a schematic cross-sectional view of an embodiment along A-Aline of the water purification device in FIG. 7; and

FIG. 9 is a schematic cross-sectional view of an embodiment along A-Aline of the water purification device having an ultrafiltration membranearranged in a first cylinder block in FIG. 7, in which arrows indicatewater flow directions during the filtration.

The objective achievement, functional characteristics and advantages ofthe invention will be further described with reference to theembodiments and accompanying drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENT

It should be understood that the preferred embodiments described hereinare not used for limiting for the invention, but for explaining theinvention.

The invention provides a water purification device, in an embodiment andwith reference to FIG. 1, FIG. 2 and FIG. 3, the water purificationdevice comprises a first pressure cylinder 10, a first cylinder block 11(See FIG. 8), a second cylinder block 12, a second pressure cylinder 13and a first connecting piece 15. The first pressure cylinder 10, thesecond cylinder block 12, the second pressure cylinder 13 and the firstconnecting piece 15 are connected to each other successively, and thefirst cylinder block 11 is accommodated in the second cylinder block 12.

The first pressure cylinder 10 comprises a first water flow end 104 anda drainage end 102. In the embodiment, the first water flow end 104 andthe drainage end 102 are arranged oppositely, the first water flow end104 is provided with an opening for the water to flow, and the drainageend 102 is formed with a first through-hole 101 for discharging thestains.

The first cylinder block 11 is configured to accommodate anultrafiltration membrane for filtering water, and two ends of the firstcylinder block 11 are provided with openings arranged in a hollow shape,preferably in a shape of hollow cylinder.

Two ends of the second cylinder block 12 are provided with openingsarranged in a hollow shape, preferably in a shape of hollow cylinder.

The second pressure cylinder 13 comprises a second water flow end 134and a water inlet end 133. In the embodiment, the second water flow end134 and the water inlet end 133 are arranged oppositely, the secondwater flow end 134 is provided with an opening for the water to flow,and the water inlet end 133 is formed with a second through-hole 131 forthe external water to flow into the second pressure cylinder; and athird through-hole 151 (See FIG. 4) for the water to flow is formed onthe first connecting piece 15.

One end of the second cylinder block 12 is connected to the first waterflow end 104, and the other end thereof is connected to the second waterflow end 134 through the first connecting piece 15. First flow passages123, one end of which near the first connecting piece 15 is sealed bythe first connecting piece 15, are formed between the first cylinderblock 11 and the second cylinder block 12 and communicated with thefirst pressure cylinder 10; the first cylinder block 11 and the secondpressure cylinder 13 are communicated with each other through the thirdthrough-hole 151. A water inlet 121 communicated with the first flowpassage 123 is formed on an outer wall of the second cylinder block 12,and a water outlet pipe 122 communicated with the first cylinder block11 is inserted into the outer wall of the second cylinder block 12.Preferably, the water inlet 121 and the water outlet pipe 122 arearranged oppositely.

Prior to the water filtration of the water purification device, thefirst through-hole 101 is in a closed state and the second through-hole131 is in an open state. During the filtration, the first through-hole101 is opened and the second through-hole 131 is closed. During flushingthe ultrafiltration membrane arranged in the first cylinder block 11,the water inlet 121 and the water outlet pipe 122 are closed, and thefirst through-hole 101 is opened, so that the water is guided into thefirst cylinder block 10 from the second through-hole 131 and flows outof the first through-hole 101.

Specifically, the water purification device is generally placedvertically during the filtration, i.e., the first pressure cylinder 10is located at the bottom of the water purification device and the secondpressure cylinder 13 is located at the top of the water purificationdevice. Prior to the filtration, the second through-hole 131 is keptopen (the second through-hole 131 is opened for exhausting gas), and thedrain outlet 101 is closed. When the water to be purified enters thefirst flow passages 123 from the water inlet 121, the water to befiltered enters the first pressure cylinder 10 first. As the water to befiltered gradually increases, the water level gradually rises, and thesecond through-hole 131 is closed, the water to be filtered is graduallyforced into the ultrafiltration membrane in the first cylinder block 11under the action of the water pressure and the pressure of the firstpressure cylinder 10 and discharged from the water outlet pipe 122 afterbeing filtered by the ultrafiltration membrane. After the filtration,stains deposited in the first pressure cylinder 10 can be discharged byopening the first through-hole 101. In this process, firstly, part ofsediment or other large-grained impurities in the water are precipitatedat the bottom of the first pressure cylinder 10 due to gravity on theone hand and due to the filtration of the ultrafiltration membrane onthe other hand. The sediment, not precipitated in the water, is blockedand remains in the first pressure cylinder 10, and the sediment notprecipitated and the sediment precipitated both can be dischargedthrough the first through-hole 101.

When the first flow passages 123 are filled with water, the water to befiltered is forced into the ultrafiltration membrane under the action ofthe water pressure and the first pressure cylinder 10. In this process,some of the impurities in the water will enter the ultrafiltrationmembrane, along with the gradual increase in the amount of impurities,the ultrafiltration membrane will gradually be clogged on the one hand,and the water will also be in secondary contamination (the water has notbeen filtered thoroughly) on the other hand, resulting in loss of thefiltering function of the ultrafiltration membrane, so that theultrafiltration membrane will be scrapped. In the water purificationdevice, the water to be filtered is forced into the ultrafiltrationmembrane mainly under the action of the water pressure and the firstpressure cylinder 10, so that the impurities in the ultrafiltrationmembrane mainly exist at a lower end (one portion of the ultrafiltrationmembrane near the first pressure cylinder 10) of the ultrafiltrationmembrane. Hence, in the embodiment, after part of the water has beentreated by the water purification device, the clean water can beintroduced into the water purification device through the secondthrough-hole 131 and flows through the ultrafiltration membrane from topto bottom, so as to scour the ultrafiltration membrane reversely(opposite to the direction of the water mainly flowing through the waterpurification device from bottom to top during the water filtration).Here, the scouring force can also be increased by pressurizing the waterflow to flush the impurities entering the ultrafiltration membrane outalong with the water flow, thus avoiding the ultrafiltration membranefrom being clogged by impurities in the water for a long-term and frombeing scrapped due to loss of the filtering function.

According to the water purification device disclosed by the invention,the water is forced into the ultrafiltration membrane under the actionof the water pressure and the first pressure cylinder 10. After thefiltration, the sewage is discharged from the first through-hole 101,and the clean water is guided out through the water outlet pipe 122. Incase that the ultrafiltration membrane is required to be cleaned, onlythe water flow is required to be guided into the water purificationdevice through the second through-hole 131, and the stains remaining inthe ultrafiltration membrane can be flushed away under the action of thewater pressure so as to prevent the ultrafiltration membrane from beingclogged and scrapped due to accumulation of excessive stains, therebygreatly improving the service life of the ultrafiltration membrane andreducing the cost of water purification.

Further, with reference to FIG. 4, a second connecting piece 14, whichis configured to connect the first cylinder block 11 and second cylinderblock 12 to the first pressure cylinder 10, is arranged between thesecond cylinder block 12 and the first pressure cylinder 10. Firstdiversion holes 1431 configured to communicate the first flow passage123 with the first pressure cylinder 10, and second diversion holes (notshown) configured to communicate the first cylinder block 11 with thefirst pressure cylinder 10 are arranged on the second connecting piece14.

Specifically, the second connecting piece 14 comprises a firstconnecting plate 141 having a through-hole formed thereon, a peripheryof the through-hole extends in a direction deviated from a surface ofthe first connecting plate 141 to form a first circular cylinder 142,and a first baffle 143 for closing ports of the first circular cylinder142 is arranged at one end of the first circular cylinder 142 away fromthe first connecting plate 141, and the second diversion holes arearranged on the first baffle 143. Peripheries of the second diversionholes extend in a direction deviated from a surface of the firstbaffle143 to form a second circular cylinder 144, and the firstdiversion holes 1431 are further arranged on the first baffle 143 on theperiphery of the second circular cylinder 144. The first circularcylinder 142 is located between the first connecting plate 141 and thesecond circular cylinder 144, and the caliber of the first circularcylinder 142 is greater than that of the second circular cylinder 144.It should be noted that, preferably, the first circular cylinder 142 isperpendicular to the first connecting plate 141; preferably, the secondcircular cylinder 144 is perpendicular to the first baffle 143.

Hereby, the first connecting plate 141 is configured to close the firstwater flow end 104 of the first pressure cylinder 10 and is fixedlyconnected (e.g. in threaded connection) to the first pressure cylinder10. The first cylinder block 11 and the second circular cylinder 144 aresleeved with and hermetically connected to each other. The secondcylinder block 12 and the first circular cylinder 142 are sleeved withand hermetically connected to each other. In this way, the tightness ofthe connection between the first cylinder block 11 and second cylinderblock 12 and the first pressure cylinder 10 is enhanced. It should benoted that, preferably, the first circular cylinder 142 isperpendicularly connected to the first connecting plate 141; preferably,the second circular cylinder 144 is perpendicularly connected to thefirst baffle 143.

Further, a second baffle 145 for closing ports of the second circularcylinder 144 is arranged at one end of the second circular cylinder 144away from the first baffle 143, and a pressurizing hole 1451 is formedon the second baffle 145.

Since the ultrafiltration membrane itself has a relatively highresistance to the water flow, in the embodiment, the water to befiltered is forced into the ultrafiltration membrane more easily byarranging the pressurizing hole 1451 in order to enhance the rate ofwater filtration. When the water to be filtered enters the firstpressure cylinder 10 (the first through-hole 101 is in a closed orpartially closed state), the water is gradually forced into theultrafiltration membrane from the first water flow end 104 by the firstpressure cylinder 10. Under the same pressure, a decrease of the area ofan opening for the water to flow into the ultrafiltration membrane meansan increase of the pressure intensity for the water to flow into theultrafiltration membrane, so that the water flow enters theultrafiltration membrane more easily and the efficiency of waterpurification is enhanced.

The second baffle 145 is arranged to bear the ultrafiltration membrane.

Further, with reference to FIG. 2, a first reinforcer 103, connected tothe second connecting piece 14, is sleeved at a position on the firstwater flow end 104 corresponding to an outer wall of the first pressurecylinder 10.

Specifically, in the embodiment, a first reinforcer 103, connected tothe second connecting piece 14, is sleeved at a position on the firstwater flow end 104 corresponding to an outer wall of the first pressurecylinder 10, in order to reinforce the connection between the secondconnecting piece 14 and the first pressure cylinder 10. The firstreinforcer 103 and the second connecting piece 14 are in threadedconnection. The first pressure cylinder 10 and the second connectingpiece 14 are in threaded connection through screw holes 1031 in FIG. 2and screw holes 1411 in FIG. 4.

Further, with reference to Fig.5, a first connecting piece 15, which isconfigured to connect the second cylinder block 12 to the secondpressure cylinder 13, is further arranged between the second cylinderblock 12 and the second pressure cylinder 13, and the third through-hole151, configured to communicate with the first cylinder block 11, isformed on the first connecting piece 15. A second reinforcer 132,connected to the first connecting piece 15, is sleeved at a position onthe second water flow end 134 corresponding to an outer wall of thesecond pressure cylinder 13.

With reference to FIG. 3, screw holes 135 are formed on the secondreinforcer 132. With reference to FIG. 5, screw holes 152 are formed onthe periphery of the third through-hole 151 of the first connectingpiece 15. The second pressure cylinder 13 and the first connecting piece15 are in threaded connection by the same screws through the screw holes135 and the screw holes 152.

With reference to FIG. 6 to FIG. 9, when the ultrafiltration membrane 20is arranged in the first cylinder block 11, second flow passages 201 areformed between the ultrafiltration membrane 20 and the interior of thefirst cylinder block 11. Since the water to be filtered is forced intothe ultrafiltration membrane 20 from both ends thereof during the waterfiltration of the ultrafiltration membrane 20, the filtered water isdischarged from outer peripheral walls of the ultrafiltration membrane20 and enters the second flow passages 201 and is finally dischargedthrough the water outlet pipe 122.

Further, with the reference with FIG. 2, the cross-sectional area of anend face of a drainage end 102 parallel to the first water flow end 10gradually decreases from the first water flow end 104 to the firstthrough-hole 101.

Specifically, the drainage end 102 can be arranged in various shapes,such as square and cylinder. However, in the embodiment, thecross-sectional area of the end face of the drainage end 102 parallel tothe first water flow end 104 gradually decreases from the first waterflow end 104 to the first through-hole 101 to facilitate discharging thefiltered impurities from the first pressure cylinder 10, so that thefiltered impurities in the water will be discharged through the firstthrough-hole 101. Any dead angle will not be formed at the bottom in thefirst pressure cylinder 10 through such arrangement of the firstpressure cylinder 10 so that the impurities will be discharged withoutbeing deposited at the bottom in the first pressure cylinder 10.

The invention further provides a method using the water purificationdevice according to any one of items to filter water, wherein the methodcomprises the following steps of:

a. placing an ultrafiltration membrane 20 in the first cylinder block11;

b. closing the first through-hole 101 and opening the secondthrough-hole 131, and injecting the water to be filtered into the flowpassages 123 through the water inlet 121 so as to exhaust the gas in thefirst cylinder block 11 and the second pressure cylinder 13; and

c. keeping the first through-hole 101 closed, and keeping the secondthrough-hole 131 open or intermittently open so as to filter the water.

First, an ultrafiltration membrane 20 is required to be added in thefirst cylinder block 11. Prior to the filtration (e.g. the filtration ofseawater), some air, which is still present in the second pressurecylinder 13 and the first cylinder block 11, is required to bedischarged so as not to cause resistance to water filtration.Specifically, prior to the filtration, the first through-hole 101 isclosed and the second through-hole 131 is opened, and the water to befiltered is injected into the flow passages 123 through the water inlet121 so as to exhaust the gas in the first cylinder block 11 and thesecond pressure cylinder 13.

During the filtration, as the gas is gradually exhausted, the waterlevel of the water injected into the flow passages123 gradually rises inthe flow passages 123, while the gas in the flow passages 123 isgradually compressed. The compressed gas generates a thrust to the waterflow, so that the water flow is forced into the ultrafiltration membrane20 under the action of this thrust and the water pressure of the waterinlet 121, and discharged through the water outlet 122 after beingfiltered by the ultrafiltration membrane 20. In this process, the secondthrough-hole 131 is kept open so that part of the stains in seawaterpass through the ultrafiltration membrane 20 and are discharged from thesecond through-hole 131. In addition, a valve, which can regulate thesize of the opening of the second through-hole 131, is arranged at aposition where the second through-hole 131 is located. The valve canchange the pressure in the second pressure cylinder 13 by regulating thesize of the opening of the second through-hole 131, wherein therelatively high pressure can make the rate of water filtration fasterwhile the relatively low pressure (i.e., the second through-hole 131 iskept partially open) facilitates discharging the stains from the secondpressure cylinder 13. Certainly, since the second through-hole 131itself is small, which has little influence on the pressure in thesecond pressure cylinder 11, the second through-hole 131 can also bekept open all the time.

Compared with the existing water purification devices, the inventionfurther has an energy-saving effect.

A test comparison is made between the water purification device of theinvention and an existing horizontal water purification device.

TABLE 1 Electric Energy Consumption Test Table Electric energy (KW-h)consumed for filtering water per ton Existing Water horizontalpurification water device purification of the S/N device invention 1 1.00.17 2 0.9 0.18 3 1.1 0.18 4 1.1 0.20 5 1.2 0.19 Mean value 1.04 0.184

It can be seen in Table 1 that the water purification device of theinvention consumes about 0.184 KW-h of electricity for filtering waterper ton, while the existing horizontal water purification deviceconsumes about 1.04 KW-h of electricity for filtering water per ton, sothat the electric energy consumption of the existing horizontal waterpurification device is 5.6 times of that of the water purificationdevice of the invention.

Analysis: As the tap water enters the flow passages 123 from a waterinlet 121, the water level gradually rises. As the water level graduallyrises, the air located at an upper end of each of the flow passages isgradually compressed while a reverse thrust is generated to the water inthe flow passages 123. The greater the pressure of the compressed airis, the greater the generated reverse thrust is, so that the water flowis forced into the ultrafiltration membrane 20 more easily and theenergy consumed for flowing the water into the ultrafiltration membrane20 is greatly reduced.

Furthermore, as the water level gradually rises from bottom to top, thewater flows back through the ultrafiltration membrane. A clearanceprovided for the water to pass through the ultrafiltration membrane 20is very small, so that the flow rate of the water passing through theultrafiltration membrane 20 is faster. At the moment, due to the fasterflow rate, all the impurities and contaminants, which are larger thanthe aperture of the ultrafiltration membrane 20, are pushed up into thesecond pressure cylinder 13 by the water flow and then discharged fromthe drain outlet 131 so that the impurities remaining in theultrafiltration membrane 20 are fewer and the service life of theultrafiltration membrane 20 is prolonged. No phenomenon that theinterior of the cylinder block and the ultrafiltration membrane 20 arecontaminated is found in the cases by keeping doing experiments with tapwater and seawater for 180 consecutive days.

The water purification device of the invention has high water yield. Atest comparison (taking tap water as an experimental subject) is madebetween the water purification device of the invention and an existinghorizontal water purification device.

TABLE 2 Water Yield Test Table Water yield (ton) per hour Existing Waterhorizontal purification water device purification of the S/N deviceinvention 1 1.5 5.8 2 2.2 6.2 3 1.7 5.9 4 1.5 6.1 5 1.9 5.9 Mean value1.76 5.98

It can be seen in Table 2 that the average water yield per hour of thewater purification device of the invention is 5.98 tons while that ofthe existing horizontal water purification device is 1.76 tons, so thatthe water yield of the water purification device of the invention isabout 3.4 times of that of the existing horizontal water purificationdevice.

Analysis: The compressed air at the upper end of the flow passage 123generates a reverse thrust to the water in the flow passage 123, thusincreasing the rate of the water flowing through the ultrafiltrationmembrane and increasing the water yield.

The above descriptions are merely preferred embodiments of the inventionand not used for limiting the patent claims of the invention, anyequivalent structure or equivalent process transformation, made by usingcontents of the description and drawings of the invention or applied toother relevant technical fields directly or indirectly, shall similarlybe regarded as falling into the scope of patent protection of theinvention.

1-12. (canceled)
 13. A water purification device, comprising: a firstpressure cylinder, a second pressure cylinder, a first cylinder block, asecond cylinder block and a first connecting piece; the first pressurecylinder, the second cylinder block, the first connecting piece and thesecond pressure cylinder are successively connected to each other, andthe first cylinder block is accommodated in the second cylinder block,the first cylinder block is configured to accommodate an ultrafiltrationmembrane for filtering water; two opposite ends of the first cylinderblock are provided with openings arranged in a hollow shape, and twoopposite ends of the second cylinder block are provided with openingsarranged in a hollow shape; the first pressure cylinder comprises afirst water flow end provided with an opening for the water to flow, anda drainage end formed with a first through-hole for discharging thestains, and the first pressure cylinder is arranged in a hollow shape;the second pressure cylinder comprises a second water flow end providedwith an opening for the water to flow, and a water inlet end formed witha second through-hole for the external water to flow into the secondpressure cylinder, and the second pressure cylinder is arranged in ahollow shape; a third through-hole for the water to flow is formed onthe first connecting piece; one end of the second cylinder block isconnected to the first water flow end, and the other end thereof isconnected to the second water flow end through the first connectingpiece; first flow passages, one end of which near the first connectingpiece is sealed by the first connecting piece, are formed between thefirst cylinder block and the second cylinder block and communicated withthe first pressure cylinder; the first cylinder block and the secondpressure cylinder are communicated with each other through the thirdthrough-hole; a water inlet communicated with the first flow passage isformed on an outer wall of the second cylinder block, and a water outletpipe, communicated with the first cylinder block, is inserted into theouter wall of the second cylinder block; prior to the water filtrationof the water purification device, the first through-hole is in a closedstate and the second through-hole is in an open state; during thefiltration, the first through-hole is opened and the second through-holeis closed; during flushing the ultrafiltration membrane in the firstcylinder block, the water inlet and the water outlet pipe are closed,and the first through-hole is opened, so that the water flows into thefirst cylinder block from the second through-hole and flows out of thefirst through-hole.
 14. The water purification device according to claim13, wherein a second connecting piece, which is configured to connectthe first cylinder block and second cylinder block to the first pressurecylinder, is arranged between the second cylinder block and the firstpressure cylinder, first diversion holes configured to communicate thefirst flow passage with the first pressure cylinder and second diversionholes configured to communicate the first cylinder block with the firstpressure cylinder are arranged on the second connecting piece.
 15. Thewater purification device according to claim 14, wherein the secondconnecting piece comprises a first connecting plate having athrough-hole formed thereon, a periphery of the through-hole extends ina direction deviated from a surface of the first connecting plate toform a first circular cylinder, and a first baffle for closing ports ofthe first circular cylinder is arranged at one end of the first circularcylinder away from the first connecting plate, and the second diversionholes are arranged on the first baffle; peripheries of the seconddiversion holes extend in a direction deviated from a surface of thefirst connecting plate to form a second circular cylinder, and the firstdiversion holes are further arranged on the first baffle on theperiphery of the second circular cylinder; the first circular cylinderis located between the first connecting plate and the second circularcylinder, and the caliber of the first circular cylinder is greater thanthat of the second circular cylinder.
 16. The water purification deviceaccording to claim 15, wherein the first circular cylinder isperpendicular to the first connecting plate and the second circularcylinder is perpendicular to the first baffle.
 17. The waterpurification device according to claim 15, wherein a second baffle forclosing ports of the second circular cylinder is arranged at one end ofthe second circular cylinder away from the first baffle, and apressurizing hole is formed on the second baffle.
 18. The waterpurification device according to claim 14, wherein a first reinforcerconnected to the second connecting piece is sleeved at a position on thefirst water flow end corresponding to an outer wall of the firstpressure cylinder.
 19. The water purification device according to claim13, wherein a second reinforcer connected to the first connecting pieceis sleeved at a position on the second water flow end corresponding toan outer wall of the second pressure cylinder.
 20. The waterpurification device according to claim 13, wherein the cross-sectionalarea of an end face of a drainage end parallel to the first water flowend gradually decreases from the first water flow end to the drainageend.
 21. The water purification device according to claim 13, whereinthe first cylinder block and the second cylinder block are arranged in ashape of hollow cylinder.
 22. A method using the water purificationdevice according to claim 13 to filter water, wherein the methodcomprises the following steps of: a. placing an ultrafiltration membranein the first cylinder block; b. closing the first through-hole andopening the second through-hole, and injecting the water to be filteredinto the flow passages through the water inlet so as to exhaust the gasin the first cylinder block and the second pressure cylinder; and c.keeping the first through-hole closed, and keeping the secondthrough-hole open or intermittently open so as to filter the water.